Acre Foot – A unit of volume commonly used to reference large-scale water resources. An acre foot equals one acre of land covered by one foot of water or 326,000 gallons. One million gallons equals 3.07 acre-feet.

AFY – Acre-feet per year, used commonly as a measure of the annual volume water supply and demand.

Biodiesel – Biodiesel is a non-petroleum based biofuel, derived from biological sources such as soybeans. It is a processed fuel that can be readily used in internal combustion engine vehicles; this distinguishes biodiesel from the straight vegetable oils (SVO) or waste vegetable oils (WVO) used as fuels in some modified engines.

Biofuel – Biofuel is any fuel that derives from biomass—recently living organisms or their metabolic byproducts, such as manure from cows. Like coal and petroleum, biomass is a form of stored solar energy. The energy of the sun is captured through the process of photosynthesis in growing plants.

Brackish Water – Water with salt concentrations of between 5,000 and 20,000 parts per million (ppm). Seawater generally has salt concentrations of greater than 20 ppm.

Btu (British Thermal Unit) – A standard unit for measuring a quantity of thermal energy, either electricity, natural gas or any other source of energy. One Btu is the amount of thermal energy required to raise the temperature of one pound of water one degree Fahrenheit at sea level.

Classification Societies – Independent global organizations that establish and apply technical standards relative to the design, construction, operation, and survey of ships.

Cogeneration – A power plant that is designed to conserve energy by using "waste heat" from generating electricity for another purpose.

Concentrate – Water that contains a high concentration of salt. Concentrate discharge from desalination plants may include constituents used in pretreatment processes, in addition to the high salt concentration seawater.

Desalination – The removal of salt from seawater.

Dynamic Positioning – A satellite-controlled system to automatically maintain a ship's position and heading by using her own propellers and thrusters. This allows operations at sea where mooring or anchoring is not feasible due to deep water, congestion on the sea bottom (pipelines, templates), or other problems.

Entrainment – Entrainment occurs when small organisms such as plankton, larvae, and fish eggs are drawn in to a water intake past any screening equipment and are subjected to pressure or temperature changes. Entrainment is generally considered to result in the death of all the entrained organisms, if not immediately, then shortly after they are discharged back into the environment where they become prey for other animals.

Exit Water – Benign water discharged similar to ambient into the ocean following the desalination process.

Feedwater – Water fed to the desalination equipment. This can be source water with or without pretreatment.

Impingement – Impingement occurs when fish and other aquatic organisms are trapped against screens used in intake systems. Impingement usually results in either injury or death to the organisms.

Kilowatt (KW) – A thousand watts. The watt is a measure of power used by electricity generating plants. One watt is equivalent to 1 Joule/second or 3.4127 Btu/hour.

kWh – The watt-hour (symbol W·h) is a unit of energy. It is commonly used in the form of the kilowatt-hour (kW·h), which is 1,000 watt-hours. One watt-hour (abbreviated W·hr) is the amount of (usually electrical) energy expended by a one-watt load (e.g., light bulb) drawing power for one hour.

Megawatt (MW) – A million watts.

Membrane – In desalination, used to describe a semipermeable film. Membranes used in electrodialysis are permeable to ions of their positive or negative charge. Reverse osmosis and nanofiltration membranes ideally allow the passage of pure water and block the passage of salts.

MGD – Million gallons per day, used commonly as a measure of water production capacity of water treatment plants and output of pump stations.

Microfiltration – In seawater desalination, a membrane used ahead of the Reverse Osmosis membranes to filter out algae, Giardia and Cryptosporidium spores, turbidity, and bacteria. Each 0.1΅m hollow fiber module is highly permeable resulting in high water production rates.

Microlayer – The upper few millimeters of the ocean. Fish eggs are sometimes concentrated in the microlayer.

Multi-Depth Intake Anti-Entrapment System – A system utilizing a telescoping intake pipe fitted with an EPA approved 316(b) Regulation wellscreen lowered below sunlight-penetrating depth to reduce the impingement and entrainment of marine organisms.

Multi-Port Dispersion System – A series of ports along the bottom of the Seawater Desalination Vessel used to return the diluted concentrate back to the ocean at very close to its original salinity level and temperature.

Product Water – The desalinated seawater delivered to the water distribution system.

Reverse Osmosis (RO) – A process of desalination where high pressure is applied continuously to the feedwater, forcing water molecules through a semipermeable membrane. Water that passes through the membrane leaves the unit as product water; most of the dissolved impurities remain behind and are discharged in a waste stream.

Salinity Plume Deterrent System – A series of chambers designed to mix concentrate with ambient seawater, dramatically reducing the salinity content and temperature to levels well within the tolerance of sea life.

Scaling – Salt deposits on the interior surfaces of a desalination plant deposited during the treatment process.

SDV – Seawater Desalination Vessel.

Seawater Desalination Vessel – An ocean going vessel with a complete, on-board desalination system that provides a steady and reliable supply of water on a large-capacity long-term, short-term water, or on-demand basis, worldwide.

Total Dissolved Solids (TDS) – Total salt and calcium carbonate concentration in a sample of water, usually expressed in milligrams per liter (mg/L) or parts per million (ppm). The state-recommended Maximum Contaminant Level (MCL) drinking water standard for total dissolved solids is 500 mg/L, the upper MCL is 1,000 mg/L, and the short-term permitted level is 1,500 mg/L.